Cultured human hepatoma cells (HEP G-2) in permanent culture have been screened for insulin receptors and several insulin stimulated cellular events. Insulin receptors are present in large numbers on these cells and meet all the classic criteria for insulin receptors including analogue specificity for competition of labeled insulin binding, displacement of bound hormone by anti-insulin receptor antibody, enhanced dissociation of bound hormone by excess unlabeled insulin. In addition, insulin stimulates glucose uptake, activation of glycogen synthase, lipogenesis, and carbon dioxide production in these cells. Human growth hormone was found to inhibit both basal and insulin-stimulated glucose uptake in cultured human fibroblasts. A 25% reduction in glucose uptake is seen with 100 micrograms per ml hGH and occurs 4-6 hours after hormone addition. Cultures of human fibroblasts from insulin resistant patients continue to be initiated and examined for insulin receptor defects.